media-libs/openal: sync with upstream

Signed-off-by: David Heidelberg <david@ixit.cz>
media-libs/openal: bump 1.16.0

based on my work and Thomas work ( v10lator@myway.de ).

Bug: https://bugs.gentoo.org/show_bug.cgi?id=523110

Signed-off-by: David Heidelberg <david@ixit.cz>